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#include "_cvaux.h"
#include "cxmisc.h"
#include "limits"

namespace cv
{

const size_t MAX_STACK_SIZE = 255;

bool checkIfNodeOutsideSphere(const Octree::Node& node, const Point3f& c, float r)
{
    if (node.x_max < (c.x - r) ||  node.y_max < (c.y - r) || node.z_max < (c.z - r) )
        return true;

    if ( (c.x + r) < node.x_min || (c.y + r) < node.y_min || (c.z + r) < node.z_min )
        return true;

    return false;	
}

bool checkIfNodeInsideSphere(const Octree::Node& node, const Point3f& c, float r)
{
    r*=r;

    float d2_xmin = (node.x_min - c.x) * (node.x_min - c.x);
    float d2_ymin = (node.y_min - c.y) * (node.y_min - c.y);
    float d2_zmin = (node.z_min - c.z) * (node.z_min - c.z);		

    if (d2_xmin + d2_ymin + d2_zmin > r)
        return false;

    float d2_zmax = (node.z_max - c.z) * (node.z_max - c.z);

    if (d2_xmin + d2_ymin + d2_zmax > r)
        return false;

    float d2_ymax = (node.y_max - c.y) * (node.y_max - c.y);

    if (d2_xmin + d2_ymax + d2_zmin > r)
        return false;

    if (d2_xmin + d2_ymax + d2_zmax > r)
        return false;

    float d2_xmax = (node.x_max - c.x) * (node.x_max - c.x);

    if (d2_xmax + d2_ymin + d2_zmin > r)
        return false;

    if (d2_xmax + d2_ymin + d2_zmax > r)
        return false;

    if (d2_xmax + d2_ymax + d2_zmin > r)
        return false;

    if (d2_xmax + d2_ymax + d2_zmax > r)
        return false;

    return true;
}

void fillMinMax(const vector<Point3f>& points, Octree::Node& node)
{
    node.x_max = node.y_max = node.z_max = std::numeric_limits<float>::min();
    node.x_min = node.y_min = node.z_min = std::numeric_limits<float>::max();

    for(size_t i = 0; i < points.size(); ++i)		
    {
        const Point3f& point = points[i];

        if (node.x_max < point.x)
            node.x_max = point.x;

        if (node.y_max < point.y)
            node.y_max = point.y;

        if (node.z_max < point.z)
            node.z_max = point.z;

        if (node.x_min > point.x)
            node.x_min = point.x;

        if (node.y_min > point.y)
            node.y_min = point.y;

        if (node.z_min > point.z)
            node.z_min = point.z;	
    }	
}

size_t findSubboxForPoint(const Point3f& point, const Octree::Node& node)
{
    size_t ind_x = point.x < (node.x_max + node.x_min) / 2 ? 0 : 1;
    size_t ind_y = point.y < (node.y_max + node.y_min) / 2 ? 0 : 1;
    size_t ind_z = point.z < (node.z_max + node.z_min) / 2 ? 0 : 1;

    return (ind_x << 2) + (ind_y << 1) + (ind_z << 0);
}
void initChildBox(const Octree::Node& perent, size_t boxIndex, Octree::Node& child)
{
    child.x_min = child.x_max = (perent.x_max + perent.x_min) / 2;
    child.y_min = child.y_max = (perent.y_max + perent.y_min) / 2;
    child.z_min = child.z_max = (perent.z_max + perent.z_min) / 2;

    if ((boxIndex >> 0) & 1)
        child.z_max = perent.z_max;
    else
        child.z_min = perent.z_min;

    if ((boxIndex >> 1) & 1)
        child.y_max = perent.y_max;
    else
        child.y_min = perent.y_min;

    if ((boxIndex >> 2) & 1)
        child.x_max = perent.x_max;
    else
        child.x_min = perent.x_min;
}

////////////////////////////////////////////////////////////////////////////////////////
///////////////////////////       Octree       //////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////

Octree::Octree() 
{
}

Octree::Octree( const vector<Point3f>& points3d, int maxLevels, int minPoints )
{
    buildTree(points3d, maxLevels, minPoints);
}

Octree::~Octree()
{
}

void Octree::getPointsWithinSphere( const Point3f& center, float radius, vector<Point3f>& out ) const
{
    out.clear();

    if( nodes.empty() )
        return;

    int stack[MAX_STACK_SIZE];
    int pos = 0;
    stack[pos] = 0;

    while(pos >= 0)
    {
        const Node& cur = nodes[stack[pos--]];

        if (checkIfNodeOutsideSphere(cur, center, radius))		
            continue;

        if(checkIfNodeInsideSphere(cur, center, radius))
        {
            size_t sz = out.size();
            out.resize(sz + cur.end - cur.begin);
            for(int i = cur.begin; i < cur.end; ++i)
                out[sz++] = points[i];;
            continue;
        }

        if (cur.isLeaf)
        {
            double r2 = radius * radius;
            size_t sz = out.size();
            out.resize(sz + (cur.end - cur.begin));

            for(int i = cur.begin; i < cur.end; ++i)			
            {
                const Point3f& point = points[i];

                double dx = (point.x - center.x);
                double dy = (point.y - center.y);
                double dz = (point.z - center.z);

                double dist2 = dx*dx + dy*dy + dz*dz;

                if (dist2 < r2)
                    out[sz++] = point;
            };
            out.resize(sz);
            continue;
        }

        if (cur.children[0])							
            stack[++pos] = cur.children[0];

        if (cur.children[1])							
            stack[++pos] = cur.children[1];

        if (cur.children[2])							
            stack[++pos] = cur.children[2];

        if (cur.children[3])							
            stack[++pos] = cur.children[3];

        if (cur.children[4])							
            stack[++pos] = cur.children[4];

        if (cur.children[5])							
            stack[++pos] = cur.children[5];

        if (cur.children[6])							
            stack[++pos] = cur.children[6];

        if (cur.children[7])							
            stack[++pos] = cur.children[7];
    }
}

void Octree::buildTree( const vector<Point3f>& points3d, int maxLevels, int minPoints)
{
    assert( (size_t)maxLevels * 8 < MAX_STACK_SIZE );
    points.resize(points3d.size());
    std::copy(points3d.begin(), points3d.end(), points.begin());
    this->minPoints = minPoints;

    nodes.clear();
    nodes.push_back(Node());
    Node& root = nodes[0];
    fillMinMax(points, root);

    root.isLeaf = true;
    root.maxLevels = maxLevels;
    root.begin = 0;
    root.end = (int)points.size();
    for( int i = 0; i < 8; i++ )
        root.children[i] = 0;

    if (maxLevels != 1 && (root.end - root.begin) > minPoints)
    {
        root.isLeaf = false;
        buildNext(0);
    }
}

void  Octree::buildNext(size_t node_ind)
{	
    size_t size = nodes[node_ind].end - nodes[node_ind].begin;

    vector<size_t> boxBorders(9, 0);
    vector<size_t> boxIndeces(size);
    vector<Point3f> tempPoints(size);

    for(int i = nodes[node_ind].begin, j = 0; i < nodes[node_ind].end; ++i, ++j)
    {
        const Point3f& p = points[i];

        size_t subbox_ind = findSubboxForPoint(p, nodes[node_ind]);

        boxBorders[subbox_ind+1]++;
        boxIndeces[j] = subbox_ind;
        tempPoints[j] = p;
    }

    for(size_t i = 1; i < boxBorders.size(); ++i)
        boxBorders[i] += boxBorders[i-1];

    vector<size_t> writeInds(boxBorders.begin(), boxBorders.end());
    
    for(size_t i = 0; i < size; ++i)
    {
        size_t boxIndex = boxIndeces[i];
        Point3f& curPoint = tempPoints[i];

        size_t copyTo = nodes[node_ind].begin + writeInds[boxIndex]++;
        points[copyTo] = curPoint;
    }

    for(size_t i = 0; i < 8; ++i)
    {
        if (boxBorders[i] == boxBorders[i+1])
            continue;

        nodes.push_back(Node());
        Node& child = nodes.back();
        initChildBox(nodes[node_ind], i, child);

        child.isLeaf = true;
        child.maxLevels = nodes[node_ind].maxLevels - 1;		
        child.begin = nodes[node_ind].begin + (int)boxBorders[i+0];
        child.end   = nodes[node_ind].begin + (int)boxBorders[i+1];
        for( int k = 0; k < 8; k++ )
            child.children[k] = 0;

        nodes[node_ind].children[i] = (int)(nodes.size() - 1);

        if (child.maxLevels != 1 && (child.end - child.begin) > minPoints )
        {
            child.isLeaf = false;
            buildNext(nodes.size() - 1);
        }        		
    }
}

}
